A variety of flavorants have been developed and proposed for incorporation into tobacco products. Illustrative of such tobacco flavorants are those described in U.S. Pat. Nos. 3,580,259; 3,625,224; 3,722,516; 3,750,674; 3,879,425; 3,881,025; 3,884,247; 3,890,981; 3,903,900; 3,914,451; 3,915,175; 3,920,027; 3,924,644; 3,937,228; 3,943,943; 3,586,387; and the like. The tobacco flavorants include compounds such as succinic anhydride; dihydroxyacetone; substituted pyridines; cinnamic acid derivatives; isovaleric acid; 6-methylhepta-3,5-dien-2-one; 2-butyl-2-butenal; 1,3-cyclohexadiene; alpha-pyrones; substituted butyrolactones; pyrazines and thiazolidines; and the like.
The high degree of volatility and ease of sublimation of flavorant additives in tobacco products have presented problems in the manufacturing operations, and have resulted in a decreased shelf-life of the products due to losses of flavorant by evaporation on storage.
In an attempt to alleviate these problems, it has been suggested that a tobacco flavorant might be adsorbed on a suitable support, such as activated charcoal or fuller's earth, and that the resultant composition might then be added to the tobacco. Attempts to pursue this method have not been satisfactory. The flavorant yields from such adsorbents have been found to be vary low. Moreover, this method obviously necessitates incorporation of the adsorbent into the tobacco, and such a foreign material can result in an undesirable appearance as well as give rise to uneven burning of the tobacco.
More recent developments have involved incorporating a low volatility organic additive to a smoking composition, which under smoking conditions is pyrolyzed into one or more fragments that function to improve the taste and character of mainstream tobacco smoke.
U.S. Pat. No. 3,312,226 describes smoking tobacco compositions which contain an ester additive such as 1-menthyl linalool carbonate. Under smoking conditions pyrolysis of the carbonate ester releases menthol which flavors the mainstream smoke.
U.S. Pat. No. 3,332,428 and U.S. Pat. No. 3,419,543 describe smoking tobacco compositions which contain a menthyl carbonate ester of a glycol or saccharide, which under smoking conditions decomposes to release free menthol into the mainstream smoke. U.S. Pat. No. 3,499,452 discloses similar smoking tobacco compositions in which a carbonate ester additive releases flavorant volatiles other than menthol.
U.S. Pat. No. 4,092,988 describes smoking tobacco compositions which contain a flavorant-release polymeric ester additive. Under smoking conditions the release of an olefinic pyrolyzate improves the flavor and aroma of mainstream and sidestream cigarette smoke.
There is continuing research effort to develop low delivery smoking compositions which generate mainstream smoke with enhanced taste and character under smoking conditions.
Accordingly, it is an object of this invention to provide smoking compositions having incorporated therein a flavorant which is characterized by lack of mobility and/or volatility at ambient temperature.
It is another object of this invention to provide smoking tobacco compositions having incorporated therein a flavorant-release composition which under normal smoking conditions imparts improved flavor to mainstream smoke and improved aroma to sidestream smoke.
It is a further object of this invention to provide novel carbonate ester compositions which are adapted to be incorporated into tobacco compositions, and which under normal smoking conditions release a phenolic type of flavorant into cigarette smoke.
Other objects and advantages of the present invention shall become apparent from the following description and examples.